U.S. patent number 4,855,375 [Application Number 07/276,598] was granted by the patent office on 1989-08-08 for styrene terminated multifunctional oligomeric phenols as new thermosetting resins for composites.
This patent grant is currently assigned to Allied-Signal Inc.. Invention is credited to James A. Wrezel, Joseph J. Zupancic, Andrew M. Zweig.
United States Patent |
4,855,375 |
Zupancic , et al. |
August 8, 1989 |
**Please see images for:
( Certificate of Correction ) ** |
Styrene terminated multifunctional oligomeric phenols as new
thermosetting resins for composites
Abstract
Thermosetting resins which are essentially vinylbenzyl
end-capped ethers of the oligomeric condensation products of
certain dihydric phenols and formaldehyde are readily polymerized
to give an extensively cross-linked polymer particularly useful in
printed circuit boards and similar laminates. Effective cost
reduction may be enjoyed by replacing up to 50% of the vinylbenzyl
moieties by other groups, such as alkyl and benzyl groups, without
destroying the usefulness of the resulting thermosetting resins.
The vinylbenzyl ether product from bisphenol-A is especially
recommended.
Inventors: |
Zupancic; Joseph J.
(Bensenville, IL), Zweig; Andrew M. (Schaumburg, IL),
Wrezel; James A. (Buffalo Grove, IL) |
Assignee: |
Allied-Signal Inc. (Morris
Township, Morris County, NJ)
|
Family
ID: |
23057311 |
Appl.
No.: |
07/276,598 |
Filed: |
November 28, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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87921 |
Aug 21, 1987 |
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Current U.S.
Class: |
526/247; 526/286;
526/313 |
Current CPC
Class: |
C07C
43/225 (20130101); C08G 8/08 (20130101); C08G
8/36 (20130101); C08G 8/28 (20130101); H05K
1/0326 (20130101) |
Current International
Class: |
C08G
8/00 (20060101); C08G 8/36 (20060101); H05K
1/03 (20060101); C08F 016/32 () |
Field of
Search: |
;526/247,286,313 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Henderson; Christopher
Attorney, Agent or Firm: Snyder; Eugene I. Wells; Harold N.
Friedenson; Jay P.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of our copending
application, Ser. No. 087,921, filed Aug. 21, 1987, all of which is
incorporated by reference, now abandoned.
BACKGROUND OF THE INVENTION
The subject matter of this application is directed toward resins
used in the manufacture of reinforced plastics. More particularly,
the resins (binders) are used in the preparation of composites
formed from fibers embedded in a polymer resin matrix. Even more
specifically this application is directed toward the use of such
resins in the preparation of circuit board laminates where the
reinforcing material is glass or quartz fiber.
To overcome some mechanical and structural limitations of plastics
it has become relatively commonplace to reinforce them with other
components. Composites formed of various fibers embedded idn a
polymer resin matrix are especially useful and susceptible to
enormous variation depending upon the nature of the fiber used, how
the fiber is utilized, and the matrix or binder for the fibers.
Materials which have been used as fibers include glass, quartz,
oriented polymers such as the aramids (Kevlar.sup.198), graphite
and boron. Whatever their composition such fibers can be used as
chopped or continuous filaments, and when used as continuous
filaments they can all be unidirectional or woven into a fabric.
The matrix can be, for example, a polyester, epoxy, polyimide,
polyetherketone or polyetherimide resin as either a thermoset or
thermoplastic material. The uses for such composites range from
airframes to tennis rackets and from boat hulls to rocket motor
casings.
A particular area of composite application is that of printed
circuit boards, especially multilayer circuit boards, for mounting
electronic components. The use of glass fabric as the reinforcing
material has become more-or-less standard and epoxy resins are most
often used as the matrix. For the fiber to exert a reinforcing
action it is necessary that the fibers be completely coated with
resin, and to achieve this the glass fiber often is surface treated
to provide sites for chemical bonding to the resin or to its
precursor or for otherwise improved adhesion to the matrix
material.
Multilayer circuit boards are laminates with alternating layers of
composite and etched copper sheet. A brief discussion of their
manufacture will aid in apprciating the propeties requisite for
such boards. A woven glass fabric is first impregnated with resin
by dipping the cloth in a resin solution, often referred to as the
varnish solustion, in what is called the A-stage. Solvent is thenr
emoved to afford a glass cloth reinforced resin, or prepreg, in
which is called the B-stage. In some cases the resin int he ppreg
may be partially cured, in other cases uncured, but in all cases
the prpreg is a non-tacky, readily handled rigid sheet of glass
cloth embedded in and coated with a resin. The finished circuit
board is prepard by laminating alternating layers of prepreg and
eched copper foil under conditions of temperature and pressure
where resin is cured, i.e., further polymerized and crosslinked to
a final unfusible, insoluble stage (C-stage).
From the above brief description some necessary and desirable
characteristics of the resin may be readily discerned. The circuit
board will be subjected to soldering temperatures and may be
operated at an elevated temperature, or experience cyclic locally
elevated temperatures because of local power generation, and thus
the thermal coefficient of expansion of the reisn should
approximate that of glass to ensure continued dimensional stability
and resistance to heat distortion. The resin should have a high
solubility in the varnish solution to ensure high resin loading.
The varnish soslution should have a sufficiently low viscosity for
even coating but not too low a viscosity as to run off the fibers.
It is necessary that the prepreg not be tacky so that it can be
readily handled and stored. The resin is desirably noncrystalline
for enhanced solubility in the varnish solution and for good film
forming properties in the prepreg. The resin should have adequate
flow at the C-stage so as to make void-free laminated bonds, with
the curing temperature somewhat higher than the glass transition
temperature (T.sub.g) of the resin to afford a wider processing
"window". The resin also should be chemically resistant to a
corrosive environment and to water vapor. To ensure that the
discrete electrical componenots on a circuit board interact only
via the etched path on the copper foil, it is desirable that the
matrix have a low dielectric constant and high resistance.
The invention to be described is an amorphous, thermosetting resin
which affords a varnish solution of high solids content with a
viscosity leading to even coating without runoff, which affords a
non-tacky prepreg, has a glass transition temperature sufficiently
below the curing temperature to afford an adequate window of
processing, and which shows excellent flow properties at the
C-stage. The final lcured resin nexhibits a low dielectric constant
and dissipation factor, a low coefficient of thermal expansion, and
a high glass transition temperature. In short, we believe our cured
resin has propeties superior to hose currently recognized as
industry standards in the lamination of circuit boards, and thus
presents outstanding benefits.
U.S. Pat. No. 4,116,936 describes thermosetting resins which are
vinylbenzyl ethers of monomeric phenols, of simple
phenol-formaldehyde condensation products commonly known as novolac
resins, and of oligomers resulting from tthe reaction of adihydric
phenol, such as bisphenol A, and a glycidyl ether. However much
these resins may represent an advance over prior art resins,
presumably because the fully cured product shows, among other
desirable properties, greater hydrolytic stability and corrosion
resistatnce, we have discovered resins whose properties are
decidedly superior in several operational aspects. In particular,
whereas the resins of our invention show desirable flow at prepreg
temperatures, they exhibit higher flow viscosity in solution at
ambient temperature, thereby minimizing runoff and leading to
improved coating uniformity. Additionally, the fully cured products
of our resins show an improved coefficient of thermal expansion, a
particularly important propety in laminate production. Thermal
expansion is a poorly understood function of the nature of the
polymer backbone as well as the nature of the end capping group.
The coefficient of thermal expansion can not be predicted, and
obtaining thermosetting resins whose theroset product has a
coefficient of thermale xpansion similar to that of, e.g., woven
glass fabric remains a hit-or-miss affair. For our purposes an
ideal fully cured product will have a coefficient of thermal
expansion of about 30 ppm. The materials of our invention approach
the goal closely.
The thermosetting resins of this invention do not appear to have a
close analogue in the prior art, with the most relevant art of Wang
et al., US. Pat. No. 4,707,558, only distantly related. The
formulae of the patentees encompass a very large niverse of
permutations, and in the case where in their formula II m'=0 and
m=1 one has a structure which is arguably, and only weakly
arguably, pertinent to the materials of this invention. But even
within such restrictions one requires a judicious choice of other
of the patentees' variables, especially A and X, to arrive at
materials even then ony remotely related to our invention.
It needs to be emphasized that although this application will
stress the utilization of the resins of our invention in the
production of multilayer circuit boards, the resins may be useful
in fabricating composites generally. Consequently, it needs to be
explicitly recognized that the resins of our invention are intended
for composite manufacture without any limitations other than those
imposed by the product specifications themselves.
SUMMARY OF THE INVENTION
The purpose of our invention is to provide thermosetting resins
whose properties make them desirable in the preparation of
composites, especially in laminated multilayer boards of a glass
fiber in a polymer matrix. An embodiment comprises the vinylbenzyl
ethers ofo the oligomeric condensation product of certain dihydric
phenols and nformaldehyde. In a ore specific embodiment the
dihydric phenol is what is commonly known as bisphenol-A. In a more
specific embodiment the vinylbenzyl ether is a mixture of meta- and
para-substituted with amethyl group. In still another embodiment
from about 50 to 100% of the ether moieties are vinylbenzyl ether
moieties, with the remainder being primary alkyl moieties
containing from 1 to about 4 carbon atoms. Other embodiments will
become apparent from the following description.
DESCRIPTION OF THE INVENTION
Our invention is a class of thermosetting resins of vinylbenzyl
ethers of the oligomeric condensation products of a dihydric phenol
and formaldehyde where from 50 to 100% of the ether groups are
vinylbenzyl moieties and the remainder, if any, are alkyl moieties
containing 1 to 10 carbon atoms or the benzyl moiety. Especially
where all the ether moieties are the vinylbenzyl group, the
extensively cross-linked polymers resulting from curing the
thermosetting resins of this invention have improved properties
with regard to their use in printed circuit boards. In particular,
they have a dielectric constant which is better than conventional
materials, a coeffcient of thermal expansion which is better than
conventional materials, show excellent solvent resistance (low
water pickup), exhibit an improved glass transition temperature,
and have a higher flow viscosity in solution at room temperature
relative to conventional materials. Our thermosetting resins may be
depicted by the formula, ##STR1##
The resins of this invention result from the etherification of
oligomers which are the condensation product ofa dihydric phenol
and formaldehyde. Therefore the product will be a mixture of
materials with varying molecular weight, that is, the resulting
resins are mixtures having discrete components of differing degrees
of oligomerization. What needs to be emphasized is that the reins
are a mixture of oligomers, and the number, n, of recurring units Q
generally will vary from 0 to 10. That is, n is 0 or an integer
from 1 to 10, where in the prferred practice of our invention it is
0 or an integer from 1 to 6. As previously mentioned, a spectrum of
oligomers typically result from the condensation reaction, and in a
desirable branch of our invention the number average of n is about
3, i.e., from 0 to about 5.
The recurring unit Q itself has the structure, ##STR2## Note that
the condensation may occur either on the same ring, as in the right
hand structure, or in different rings, as in the left hand
structure. The aromatic rings in the recurring unit Q are either
joined directly or are separated by an intervening atom furnished
by the moiety X. Therefore, s is 0 or 1.
Each of the moieties X may be either a methylene [CH.sub.2 ],
isopropylidene [C(CH.sub.3).sub.2 ], hexafluoroisopropylidene
[C(CF.sub.3).sub.2 ], an oxygen, sulfur, sulfonyl [S(O).sub.2 ],
carbonyl [C(0)], or a dioxyphenylene group [OC.sub.6 H.sub.4 O],
where the oxygens of the latter generally are para or meta to each
other. In a favored embodiment is isopropylidene.
Each of the aromatic rings may bear substituents or may be
completely unsubstituted. Thus, R.sub.1 and R.sub.2 are
independently selected from moieties such as hydrogen, alkyl
moieties containing from 1 to 10 carbon atoms, the phenyl moiety
alkoxy moieties containing from 1 to 10 carbon atoms, and phenoxy,
C.sub.6 H.sub.5 O. Examples of suitable alkyl moieties include
methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl,
and decyl moieties. The methyl and tert-butyl groups are preferred
alkyl moieties in the practice of our invention, although hte
variant where R.sub.1 =R.sub.2 =H is quite desirable.
The basic resins also can be readily modified to be flame retardant
by incorporating halogen atoms into the aromatic rings. Thus, Z may
be a halogen atom, especially bromine, and where the aromatic ring
is halogenated a and b is an integer from 1 to 4. Polyhalogenated
materials are desired as flame retardants, which means that a and b
are recommended to be 2, 3, or 4. Where the aromatic rings are not
halogen substituted then both a and b are 0.
The oligomeric condensation products have a multiplicity of
phenolic hydroxyl groups substantially all of which are end-capped
as either groups in our thermosetting resins. The best case results
where the ether portion, E, is a vinylbenzyl moiety, that is, of
the structure. ##STR3## which may be either the meta- or
para-isomer, and which usually is a mixture of othe meta- and
para-isomers. However desirable it may be to have all the phenolic
hydroxyls end-capped with vinylbenzyl moieties, there is a decided
cost advantage when fewer than all of the ether groups are
vinylbenzyl, usually at the expense of a somewhat lower dielectric
constant. In our invention it is required that at least 50% of the
E moieties be a vinylbenzyl moiety, but a product with better
performance characteristics results when from 70 to 100% of the
ether groups are vinylbenzyl, and the best product results when 95
to 100% of such groups are vinylbenzyl.
In those cases where less than all of the ether groups are
vinylbenzyl, then we are partial to resins where E is an alkyl
group containing from 1 to 10 carbons or oa benzyl group. Where E
is an alkyl group, the primary alkyl groups are given priority,
especially the primary lower alkyl groups containing from 1 to 4
carbon atoms. Thus, the most desirable alkyl groups consist of
methyl, ethyl, 1-propyl, 1-butyl, and 1-methyl-1-propyl. Other
alkyl groups are represented by 1-pentyl, 1-hexyl, 1-heptyl,
1-octyl, 1-nonyl, 1-decyl, 2-methyl-1-butyl, 3-methyl-1-butyl,
2,3-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-methyl-1-pentyl, and
so forth. However, it is to be emphasized that a benzyl group also
operates quite satisfactorily in the practice of our invention.
The resins of our invention may be prepared by acid catalyzed
condensation of dihydric phenols with formaldlehyde followed by
end-capping substantially all the pneolic hydroxyls by converting
them to ethers. Acid catalyzed condensation is preferred to avoid
the formation of terminal hydroxy methylene groups, --CH.sub.2 OH.
End-capping by ether formation can be effected by any suitable
means, such as by reating the phenolic condensation product with an
alkyl or benzyl halide in a basic medium. The resulting
thermosetting resins are readily polymerized with attendant
cross-linking by a variety of curing means. In a preferred mode,
curing is effected by thermal means, generally autoinitiated by
heating the resin in air at a temperature between abou 100 and
250.degree.C., and more particularly between about 120 and
200.degree.C. In practice multilayer boards may be laminated at a
temperature between abou 150 and 200.degree.C. for 0.5-5 hours with
postcuring ata bout 180-250.degree.C. for about 0.5-24 hours.
Curing also may be brought about by chemical means using a free
radical initiator such as azo-bis-isobutyronitrile, benzoyl
peroxide, di-t-butyl peroxide, etc. Curing may be effected as well
by irradiation, especially by visible and ultraviolet light in the
presence of a suitable photoinitiator. Whether thermal, chemical,
or photochemical curing is performed, the resin becomes extensively
cross-linked and sets to an infusible, insoluble glassy solid.
The materials of our invention also can be blended with other types
of vinylbenzyl ethers of functionality greater than or equal to 2
to provide A-stage varnish solutions with tailorable viscosity and
variable properties in the cured product such as glass transition
temperature, heat distortion temperature, fracture toughness, etc.
For example, our resins could be blended with various styrenated
bisphenols to raise cross-link density and improve processability
of the bis-styryl compound. The materials of our invention are
polymers of moderate functionality (i.e., number of vinylbenzyl
groups per molecule) and viscosity and they can be incorporated to
reduce crystallinity of various styrenated bisphenols where the
bisphenols are exemplified by the formula ##STR4## with W being
--0--,--C(CH.sub.3).sub.2 --, SO.sub.2 --, --CO--, and so forth to
raise the resin solids content in the A-stage varnish solution, to
raise the resin content in the B-stage, and to reduce the amount of
resin flow in the C-stage. High-to-moderate molecular weight
poly(vinylbenzyl ethers) also may be useful for improving the shelf
life of other styrenated oligomers, and may raise the ductility of
the otherwise brittle laminate, such as in the case of styrenated
bisphenol A.
The following examples are merely illustrative of our invention and
are not limiting in any way.
Claims
What is claimed is:
1. A thermosetting resin which is a vinylbenzyl ether of the
oligomeric condensation product of a dihydric phenoland
formaldlehyde and with the formula: ##STR5## where the recurring
unit Q has the structure, ##STR6## and n is an integer from 1 to
10; s is 0 or 1;
each X is independently selected from the group consisting of
CH.sub.2, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2, S(O).sub.2, and
OC.sub.6 H.sub.4 O;
each R.sub.1 and nR.sub.2 is independently selected from the group
consisting of hydrogen, alkyl and alkoxy moieties containing 1 to
10 carbon atoms, phenyl and phenoxy;
a and b are independently 0 or integers from 1 to 4;
Z is C1 or Br;
E is selected from the group consisting of the vinylbenzyl moiety,
alkyl moieties containing 1 to 10 carbona toms, or benzyl, subject
to the constraint that at least 50% of all E's are the vinylbenzyl
moiety.
2. The resin of claim 1 where each R.sub.1 and R.sub.2 is selected
from the group consisting of hydrogen, methyl, and tert-butyl
moieties.
3. The resin of claim 2 where all R.sub.1 and R.sub.2 are
hydrogen.
4. The resin of claim 2 where all R.sub.1 and R.sub.2 are
methyl.
5. The resin of claim 1 where s is 1 and X is
C(CH.sub.3).sub.2.
6. The resin of claim 1 where Z is Br and each of a and b is an
integer from 1 to 4.
7. The resin of claim 1 where E is primary alkyl moiety containing
from 1 to 10 carbon atoms.
8. The resin of claim 7 where the alkyl moietty containsn 1 to 4
carbon atoms.
9. The resin of claim 1 where E is benzyl.
10. The resin of claim 1 where from 70 to 100% of the E mooieties
are the vinylbenzyl moiety.
11. The resin of claim 10 where from 95 to 100% of the E moieties
are vinylbenzyl moieties.
12. The resin of claim 1 where n is an integer from 1 to 6.
13. The resin of claim 1 where the number average of n is about 3.
Description
EXAMPLE 1
Preparation of Styrene Terminated Bisphenol-A Formaldehyde
(STBPA-F). Bisphenol-A formaldehyde resin was prepared as follows.
150.0 g (0.658 moles) of bisphenol-A was dissolved in 500 ml of
ethanol in a 1 liter round bottom flask equipped with condenser and
magnetic stirrer. To his reaction mixture was added 0.5 ml of
concentrated sulfuric acid. The solution was heated to reflux and
then 14.5 g (0.151 moles) of paraformaldehyde was added gradually
to the reaction. The reaction was heated at reflux with stirring
for 48 hours and then allowed to cool to room temperature. The
reaction was neutralized with aqueous sodium hydroxide solution and
then concentrated under vacuum, yielding 130.3 g of viscous syrup,
with a M.sub.w =362.
50.0 g (0.1062 moles) of bisphenol-A formaldehyde resin and 71.35 g
(0.4675 moles) vinylbenzyl chloride (60/40 meta/para isomer ratio)
were dissolved in 110 ml of acetone in a three neck-round bottom
flask equipped with condenser, addition funnel, thermometer,
mechanical stirrer and nitrogen purge. The reaction mixture was
heated at reflux (65-70.degree.C. temperature) for a period of one
hour, following which a solution of 41.83 g (0.746 moles) of
potassium hydroxide in 93 ml of methanol was added to the warm
reaction mixture over an internal of one hour. The reaction was
stirred thereafter ambient temperature for a period of 24 hours.
The reaction mixture was recovered, dried over magnesium sulfate,
filtered, and concentrated under vacuum. The resulting oil was
dried in a vacuum oven at ambient temperature overnight and yielded
24.5 g of resin.
EXAMPLE 2
Preparation of Cured STBPA-F. 3.3 g of STBPA-F of Example 1 was
placed in a flat casting dish and cured by heating in an oven at a
temperature of 120.degree.C. for a period of 2 hours, followed by a
16 hour cure at 160.degree.C. and a 2 hour cure at 200.degree.C.
Following this, the sample was then post-cured for a period of 2
hours at 225.degree.C. and recovered. The cured polymer was found
to have a glass transition temperature (Tg) of greater than
300.degree.C., a minor softtening point (Tsp) (measured via Thermal
Mechanical Analysis (TMA)) at 165 .+-.5.degree.C., a coefficient of
thermal expansion from 25.degree.to 165.degree.C. of 40.+-.2
ppm/.degree.C and from 25.degree.to 260.degree.C. of 65.+-.3
ppm/.degree.C. The dielectric constant at 1 MHz and dissipation
factor at 0% and 50% relative humidity are summarized in the
following table.
TABLE 1 ______________________________________ Relative Dielectric
Dissipation Humidity Constant Factor
______________________________________ 0% 2.94 .+-. 0.27 0.004 .+-.
0.001 50% 3.25 .+-. 0.17 0.013 .+-. 0.001
______________________________________
EXAMPLE 3
Preparation of Cured STBPA-F from chloroform Solution. 2.0 g of
STBPA-F resin of Example 1 was dissolved in about 10 milliliters of
ochloroform. The resulting solution was transferred to a flat
castingn dish and heated on a hot plate to remove a major portion
of the chloroform solvent. The sample was then cured in an oven at
120.degree.C. for 2 hours, followed by 16 hours at 160.degree.C.
and 2 hours at 200.degree.C.. The sample was post cured at
225.degree.C. for 1 hour. The cured polymer was found to have the
following properties: glass transition temperature (Tg)
>300.degree.C., coefficient of thermal expansion from 25 to
260.degree.C. (.alpha..sub.260) of 59.+-.4 ppm/.degree.C. and a
dielectric constant and dissipation factor (1 MHz) at 0% relative
humidity of 2.63 .+-.0.17 and 0.007.+-.0.001, respectively.
EXAMPLE 4
Preparation of Styrene Terminated Polybrominated Bisphenol-A
Formaldehyde (STBBPA-F). 40.57 (0.086 moles) of bisphenol-A
formaldlehyde resin, 40 milliliters of carbon tetrachloride, 84
milliliters of methanol and 1.99 g of potassium bromide were
charged into 500 ml three neck-round bottom flask equipped with
condenser, addition funnel, nitrogen purge and magnetic stirring
bar. The reaction vessel was placed in a water bath and heated to a
temperature of about 50.degree.C. To this 2-phase reaction mixture
was added 41.25 milliliters (0.800 moles) of bromine dropwise over
a 4 hour period. At the end of this time 80 milliliters of water
was added to the reaction mixture and a distillation head attached
to the reaction vessel, and the volatile products were distilled
off at atmospheric pressure. The remaining residue was taken up in
160 milliliteres of dichloromethane and the organic phase was
washed three times with 80 milliliters of water and then twice with
80 milliliteres of 10% aqueous sodium bisulfite to remove any
residual bromine which may be present. The organic phase was washed
with 80 milliliters of water and dried over sodium sulfate. The
methylene chloride was removed under vacuum and then azeotropic
drying with ethanol gave 80.70 grams of product.
40.0 g (0.425 moles) of the above polybrominated bisphenol-A
formaldehyde resin and 28.54 g (0.187 moles) of vinylbenzyl
chloride (60/40 meta/para isomer ratio) were dissolved in 90 ml of
acetone in a three neck-round bottom flask equipped with condenser,
addition funnel, thermometer, mechanical stirrer and nitrogen
purge. The reaction mixture was heated to reflux (65-70.degree.C.
temperature) for a period of one hour, following which a solution
of 12.54 g (0.224 moles) of pottassium hydroxide in 28 milliliteres
of methanol was added to the warm reaction mixture over a period of
one hour. Thereafter the reaction was stirred at ambient
temperature for a period of 24 hours. The reaction mixture was
recovered, dried over magnesium sulfate, filtered and concentrated
under vacuum. The resulting oil was dried in a vacuum oven at
ambient temperature overnight and yielded 30.8 g of resin.
EXAMPLE 5
Preparation of Cured STBBPA-F. 5.0 gof STBBPA-F resin of Example 4
wazs placed in a flat casting dish and cured by heating in an oven
at a temperature of 120.degree.C. for 2 hours, followed by a 16
hour cure at 160.degree. C. and a 2 hour cure at 200.degree.C. The
sample was post-cured for a period of 2 hours at 225.degree.C. and
recovered. The cured polymer was found to have the following
properties: glass transition temperature (Tg)>250.degree.C., and
dielectric constant (1 MHz) and dissipation factor at 0 to 50%
relative humidity as tabulated in Table 2.
TABLE 2 ______________________________________ Relative Dielectric
Dissipation Humidity Constant Factor
______________________________________ 0% 3.01 .+-. 0.16 0.002 .+-.
0.001 50% 2.98 .+-. 0.02 0.009 .+-. 0.001
______________________________________
EXAMPLE 6
Preparation of Cured STBBPA-F from chloroform Solution. 2.0 g of
STBBPA-F resin of Example 4 was dissolved in 10 milliliters of
chloroform. The resulting solution was transferred to a flat
casting dish and heated on a hott plate to remove the majority of
the solventt, the sample was then cured in an oven at 120.degree.C.
for 2 hours, followed by 16 hours at 160.degree.C. and 2 hours at
200.degree.C. The sample was post-cured at 225.degree.C. for 1
hour. The cured polymer was found to have the following properties:
glass transition temperature (Tg)>250.degree.C., and dielectric
constant and dissipation factor at 0% and 50% relative humidity as
tabulated in table 3.
TABLE 3 ______________________________________ Relative Dielectric
Dissipation Humidity Constant Factor
______________________________________ 0 2.82 .+-. 0.16 0.004 .+-.
0.002 50 2.77 .+-. 0.008 0.012 .+-. 0.001
______________________________________
EXAMPLE 7
Preparation of Cured STBPA; Comparison of Selected Propeties.
Styrene terminated bisphenol-A was prepared according to the method
of Steiner (U.S. Pat. No. 4,116,936) by reacting vinylbenzyl
chloride with bisphenol-A. This resin was cured by taking 2.0 g of
STBPA and was dissolved in about 10 milliliters of chloroform in a
flat casting dish and heated on a hot plate to remove the majority
of the solvent. The sample was then cured in an oven at
120.degree.C. for 2 hours, followed by 16 hours at 160.degree.C.
and 2 hours at 200.degree.C.. The sample was postcured for 1.5
hours at 225.degree.C.. The cured polymer had the following
properties: glass transition tempeature (Tg)>250.degree. C,
minor softening point (Tsp) (measured via TMA) at 168
.+-.11.degree. C., a coefficient of thermal expansion from
25.degree.to 168.degree. C. of 57 .+-.8 ppm/.degree.C. and from
25.degree.to 260.degree. C. of 71 .+-.23 ppm/.degree.C.. The
dielectric constant at 1 MHz and dissipation factor at 0% and 50%
relative humidity are summarized in the following table.
TABLE 4 ______________________________________ Relative Dielectric
Dissipation Humidity Constant Factor
______________________________________ 0 2.93 .+-. 0.11 0.003 .+-.
0.002 50 3.15 .+-. 0.14 0.013 .+-. 0.001
______________________________________
* * * * *